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Topic: Drivetrain Advice (Read 8114 times)

I am in the process of building a touring bike and am looking for advice on the drivetrain. I want to use a 12-34 cassette with a XT derailleur, a mountain crankset, 22-32-44 or 26-36-48, and STI shifters. I am told a Dura-Ace or Ultegra front derailleur will not work on these chainrings and a XT front derailleur will not work with a STI shifter. I have been told Shimano makes a Nexave front derailleur that will work but only on a 8 speed cassette. I would like to stay with a 9 speed. I thought about a bar end shifter for the front derailleur but would like to stay with the STI. Any advice or opinions would be appricated.Thanks,Jim

Not sure about Dura Ace but I'm pretty sure an Ultegra front derailleur will work fine with a 26-36-48 crankset. My son had a Trek that came with an RSX crank with 26-36-46T chainrings and a 105 (same geometry as Ultegra) front derailleur. It shifted fine with STI despite the small "big" ring.

Also, I've modified a bunch of 8-speed and 9-speed Shimano road triple cranks from 30-42-52T to 26-42-52T and they also shift well with 105 or Ultegra front derailleurs even though the range exceeds Shimano's published recommendations.

The point of all of this is that the road front derailleurs are pretty tolerant of chainring sizes and total teeth. You should be fine.

I changed the gearing on my Cannondale to get something better and went with 24/39/48. Shifts fine with a Tiagra derailleur and shifters. I have heard if you go to a 44 that the derailleur cage is the wrong curvature to work well. I would think the Nexave front derailleur would work whether it was meant for 8 or 9 speeds, but you may want to get a more experienced opinion on that one.

If you're going to spend that much money you might look into a Rohloff 500/14 Speed hub. Gives the same gears as a mountain bike but cost from $900 to $1200. I bought one two years ago and won't go back to using derailluers. No derailluer problems because I have none. I also put on a Schlumph speed drive and have a gear inch from 14inches to 124inches. If you're a weight weenie and worried about it, the Rohloff will add an extra 1 and 1/2 pounds to the bike. But you won't have to worry about breakdowns with this thing. The Rohloff will also save you on chain wear. Besides the worry free maintanence, being able to shift gears, and multiple gears at a time, anytime, at a full stop at busy intersection, or going up a steep hill or peddeling backwards, is a new experience.

You really got try one before you start knocking it. 18,000 miles on the Rohloff, including the whole CDT and from Montana to Florida, and 4200 on the Schlumph so far without a breakdown, of any kind, and I have better gearing than a mountian bike and road racing bike combined. Now if I can just find tires that won't go flat.

Other than cost and weight, the Rohloff hub has two more disadvantages/problems:

1. The shifter is intended for straight bars and not suitable for drop bars. I've heard of a couple of home made adapters to allow the use of drop bars but they were somewhat jury-rigged and required a fair bit of do-it-yourself construction.

2. The Rohloff hub requires horizontal dropouts to properly tension the chain, rather like a fixed gear or single speed setup. If you get very lucky with your chainring/cog/chainstay length combination vertical dropouts can work but you can't be sure until you try it. Rohloff does offer a chain tension device (sort of a stripped down rear derailleur) to allow vertical dropout use but that defeats some of the simplicity of the installation.

BTW, I just looked up the "Schlumpf speed drive" on Sheldon Brown's web site. My first thought was that it was one of his annual April 1 articles but apparently it's real. What is also is is EXPENSIVE! One of these plus the Rholoff hub totals over $1300.

The cost of a couple of chainrings and a derailleur or even a new crank is negligable in comparison.

Best money I ever spent. In the past 5 years, before purchasing both the Shlumpf and Rohloff, I have spent over $3,700 in just keeping up my two bikes. The past two years with only the Rohloff, and the only bike I ride now, I spent about $50 on chains and oil changes, in two years. I ride the bike everyday to work and back. I tour on it and take it out in the mountains.

As far as the road bike handle bars go. I've heard that twist shifter doesn't work on road bars, but that didn't stop Sheldon Brown from putting one on his bike. Surprisingly, I've never had a problem with the rear chain tensioner, but it would have been nice if my bike had horizontal dropouts. My next bike will be made with dropouts specifically for the Rohloff. I'll sell my bike but I won't sell this hub. I almost gave up on it till after it finally broke in, about 800 miles. Now I won't ever go back to derailleur systems.

And no. I don't work for Rohloff or even own a bike store. I'm just really pleased with this hub, and haven't had to do anything but change the oil once a year. Try putting 18,000 miles, (actually I have close to 19,000 miles on it) on any derailleur, cassette and hub combo system, without problems or constant adjustments, and you'll aslo go through three times as many chains.

But hey, it's not for eveyone. Best investment I ever made for my bike.

Your experience with the Rholoff hub has been good and I've heard complimentary things about them from other riders so they do work.

However, I think your economics are a bit off as 18,000+ miles on a conventional drive train isn't particularly difficult. I put over 28,000 miles on an 8-speed 105 STI triple drivetrain and my maintainance consisted of five cassettes ($25 each) and five chains ($15 each) in that time. Both the derailleurs and crank needed no maintainance other than periodic lubing and superficial cleaning. My experience is typical, not unusual.

What I don't understand is how you spent $3700 in maintainance costs in five years. What on earth did you do to those bikes to need that level of expense?

Actually I spent a lot more than that. $3,700 was just the cost for replacing rear hub, cassettes, and derailleurs for downhill races. Now I switch out the Rohloff (the whole wheel) from my downhill bike to my hardtail for commuting and touring.

I didn't include the cost for new rims and wheel building. I got very good at wheel building. I haven't had to rebuild the wheel since I strung up the Rohloff. (knock wood). My Rohloff has already paid for itself, several times over. And some people have over 100,000 miles on this hub, and no one knows how far it will go before it break downs. Rohloff doesn't even know yet. Another great advantage of the Rohloff is being able to shift, anytime. No more anticipating how many revolutions I'll have to make to get my derailluer to upshift or downshift before, during, or after a technical. The Rohloff goes into whatever gear I want instantly. Which is real nice when commuting and waiting to cross an intersection at a full stop, or finding yourself in too high of gear while going up hill and hoping you can force the crank that extra revolution to downshift, without snaping the chain or derailluer.